Dr. Jekyll's confession

Summary 

Dr. Jekyll explains in the letter why he had invented the potion. He says that he wanted to separate good from evil and he experiment whit itself.
When he found the right ingredients, suffered a transformation and he converts in Mr. Hyde.
Over time they became involuntary transformations and could not control them.

After the murder of Sir Carew, Dr. Jekyll tried to avoid becoming Mr. Hyde but he failed. 
One day, when he being in the street, he turned into Mr. Hyde. He tought to write to Dr. Lanyon for help and instructing him to his home for took the necessary ingredients to make the potion. Dr. Lanyon follow his instruccions anda Mr. Hyde transformed in Dr. Jekyll infront of him. Dr. Lanyon disapproving the experiment and never wanted to know nothing more about Dr. Jekyll.

After that Dr. Jekyll shut himself up in his laboratory.

When Dr. Jekyll turned into Mr. Hyde in the last time, decides to suicide because it is the only way to end this miserable life.